Effective Data Visualisation

Data Exploration and Visualisation

Dr Zak Varty

More Than A Pretty Picture


Visualisation is a key skill in your data science tool kit:

  • Rapidly explore data sets

  • Model evaluation and diagnostics

  • Sharing evidence

  • Telling compelling stories.

Reflective exercise, not a tutorial or rulebook.

Warming stripes graphic on the cover of “The Climate Book”

1: Think About Your Tools

Data visualisation tools

Coffee consumption, visualised. Jaime Serra Palou.

Selecting your tools: Analogue or Digital

Caffeination vs sleep, shown in lego. Elsie Lee-Robbins

Staying in the tidyverse: {ggplot2}


Layered creation of graphics from tidy data.

Learning {ggplot2}:


2: Think About Your Medium

Where will your plot go?


Use cases: exploratory analysis, presentation, report / paper, data journalism.


Considerations:

  • Time investment vs quality
  • Image size / format
  • Time spent with graphic

File types


Bitmap Graphics: png, jpeg, gif

  • made of pixels
  • smaller file size

Vector Graphics: pdf, eps, svg

  • made of vectors
  • larger file size

3: Think About Your Audience

Know your audience

Who is the intended audience for your visualisation?

What knowledge do they bring with them?

What assumptions and biases do they hold?


Creating personas for distinct user groups can be helpful.

Preattentive Attributes

First impressions count

Issues with scales, area and perspective

Visual perception


Default colour scales


Desaturated colour scales

Alt text, titles and captions

Captions

Describes a figure or table so that it may be identified in a list of figures and (where appropriate).

Alternative text

Describes the content of an image for a person who cannot view it. (Guide to writing alt-text)

Titles

Give additional context or identify key findings. Active titles are preferable.

Graph to show how X varies with Y

4: Think About Your Story

Data visualisation as storytelling


  • Where does your purpose fall on this triangle?


  • No such thing as neutral presentation.


  • Start with a hook.

5: Think About Your Guidelines

Standardise and document it


Decisions cost time, energy and money. (DRY)


Consider your design choices carefully and write down your decisions and reasoning. (DRY)


This will form the basis of your own style-guide for data visualisation.

Style guides for data visualisation

Wrapping Up


Think about your tools

Think about your medium

Think about your audience

Think about your story

Think about your guidelines

Image Credits